U.S. patent application number 12/157912 was filed with the patent office on 2008-12-18 for systems and methods for providing device-to-device handshaking through a power supply signal.
This patent application is currently assigned to Apple Inc.. Invention is credited to Doug Farrar, Lawrence Heyl, Brian Sander.
Application Number | 20080309313 12/157912 |
Document ID | / |
Family ID | 39645349 |
Filed Date | 2008-12-18 |
United States Patent
Application |
20080309313 |
Kind Code |
A1 |
Farrar; Doug ; et
al. |
December 18, 2008 |
Systems and methods for providing device-to-device handshaking
through a power supply signal
Abstract
Handshaking circuits are provided in a communications cable and
in a device operable to be mated with the communications cable.
Before a device can utilize the power supply signal of such a
communications channel, the two handshaking circuits must
sufficiently identify one another over a power supply signal with a
decreased voltage. The decreased voltage allows for a cable plug to
be provided with a safe, protected power that cannot cause harm to
a human. The decreased voltage also reduces the chance that a
device can receive a primary power supply signal from the cable
before the device sufficiently identifies itself. Accordingly, a
laptop may be connected to a portable music player, but the voltage
of the power supply signal provided by the laptop to the cable may
be decreased on-cable until the handshaking circuit of the portable
music player sufficiently performs a handshaking operation with a
on-cable handshaking circuit.
Inventors: |
Farrar; Doug; (Los Altos,
CA) ; Heyl; Lawrence; (Colchester, VT) ;
Sander; Brian; (San Jose, CA) |
Correspondence
Address: |
ROPES & GRAY LLP
PATENT DOCKETING 39/361, 1211 AVENUE OF THE AMERICAS
NEW YORK
NY
10036-8704
US
|
Assignee: |
Apple Inc.
Cupertino
CA
|
Family ID: |
39645349 |
Appl. No.: |
12/157912 |
Filed: |
June 13, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60934733 |
Jun 15, 2007 |
|
|
|
Current U.S.
Class: |
323/351 |
Current CPC
Class: |
Y02D 10/14 20180101;
G06F 13/4081 20130101; Y02D 10/151 20180101; G06F 21/81 20130101;
Y02D 10/00 20180101; G06F 1/266 20130101 |
Class at
Publication: |
323/351 |
International
Class: |
H02M 3/156 20060101
H02M003/156 |
Claims
1. A system comprising: a cable including a first plug and a second
plug; a first circuit located on said cable; a device, wherein a
second circuit is located on said device that receives a power
supply signal in a form regulated by said first circuit and
instructs said first circuit to provide said power supply signal in
unregulated form.
2. A method comprising: receiving a power supply signal;
stepping-down said power supply signal; recognizing said
stepped-down power signal for a pre-determined amount of time;
introducing current spikes into said power supply signal after said
stepped-down power signal has been recognized for said
pre-determined amount of time; recognizing said current spikes; and
stepping-up said voltage in response to said recognized current
spikes.
3. A method comprising: receiving a power supply signal on a first
plug of a cable; stepping-down, on said cable, the voltage of said
power supply signal; providing said stepped-down power supply
signal to a second plug of said cable, wherein said second plug is
mated with a device; receiving information from said device through
said stepped-down power signal provided to said device.
4. The method of claim 3, wherein said information provides
instructions to perform an operation on said cable to said
stepped-down power supply signal.
5. The method of claim 4, wherein said operation comprises
stepping-up said stepped-down power supply signal.
6. A method comprising: determining whether the voltage of a
received power supply signal is within a particular range; if the
voltage of said power supply signal is within said particular
range, manipulating the current of said power supply signal;
recognizing said manipulated current; increasing the voltage of
said received power supply signal above said particular range in
response to said recognized manipulated current.
7. The method of claim 6, wherein said power supply signal is
received from an on-cable circuit, said recognizing is performed on
a device, and said increasing is performed by said on-cable
circuit.
8. A method comprising: receiving on a device a first handshake
signal from an on-cable circuit, wherein said first handshake
signal is provided in a power supply signal for said device;
providing a second handshake signal from said device to said
on-cable circuit in response to the first handshake signal, wherein
said second handshake signal is provided in said power supply
signal; and changing at least one characteristic of said power
supply signal in response to said second handshake signal.
9. A system comprising: a first circuit comprising: an input node
for receiving a power signal; a voltage detector for determining
whether said power signal meets a voltage threshold; a timing
circuit, wherein said timing circuit is enabled based on whether
said voltage threshold is met and said timing circuit performs a
counting operation so long as said voltage threshold is met; and a
pulse generator circuit, wherein said pulse generator circuit
provides current pulses to said power signal after said counting
operation is performed for a pre-determined amount of time.
10. The system of claim 9, further comprising a second circuit for
providing said power signal and detecting said current pulses in
said power signal.
11. The system of claim 10, further comprising a second circuit for
providing said power signal, said first circuit is provided on a
device, and said second circuit is provided on a cable operable to
electrically couple with said device.
12. An on-cable handshaking circuit comprising: an input node for
receiving a power supply signal; a first circuit, wherein said
first circuit decreases the voltage of said power supply signal
received at said input node and provides said decreased power
supply signal to an output node; and a current detector, wherein
said current detector provides a control signal based on the
current of said power supply signal on said output node and the
voltage of said power supply signal on said output node is
increased in response to said control signal.
13. The on-cable handshaking circuit of claim 12, wherein a device
is coupled to said output node and introduces current pulses into
said output node in order to cause said current detector to
generate said control signal.
14. An on-device handshaking circuit comprising: an input node for
receiving a power signal; a voltage detector for determining
whether said power signal meets a voltage threshold; a timing
circuit, wherein said timing circuit is enabled based on whether
said voltage threshold is met, said timing circuit performs a
counting operation based on whether said voltage threshold is met,
and said timing circuit provides a control signal; and a pulse
generator circuit, wherein said pulse generator circuit provides a
current pulse to said power signal based on said control
signal.
15. A method for using a power supply signal between a first device
and a second device, the method comprising: receiving the power
supply signal with a first handshaking circuitry of the first
device; changing a first characteristic of the power supply signal,
wherein the first characteristic is changed by the first
handshaking circuitry; recognizing the changed first characteristic
with a second handshaking circuitry of the second device;
introducing current spikes into the power supply signal in response
to recognizing the changed first characteristic, wherein the
current spikes are introduced by the second handshaking circuitry;
recognizing the current spikes with the first handshaking
circuitry; and altering a second characteristic of the power supply
signal in response to recognizing the current spikes, wherein the
second characteristic is altered by the first handshaking
circuitry.
16. The method of claim 15, wherein changing the first
characteristic of the power supply signal comprises stepping-down
the voltage level of the power supply signal.
17. The method of claim 15, wherein altering the second
characteristic of the power supply signal comprises stepping-up the
voltage of the power supply signal.
18. The method of claim 15, wherein recognizing the changed first
characteristic comprises determining that the voltage level of the
power supply signal is within a particular range for a
pre-determined amount of time.
19. The method of claim 15, wherein the first device is a cable
that is coupled to the second device, and wherein the first
handshaking circuitry is located within the cable.
20. The method of claim 19, wherein the cable comprises one or more
plugs.
21. The method of claim 20, wherein at least one of the plugs is a
Universal Serial Bus plug.
22. The method of claim 20, wherein at least one of the plugs is a
30-pin connector plug.
23. The method of claim 15, wherein the first device is a power
supply, and wherein the first handshaking circuitry is located
within the power supply.
24. The method of claim 15, wherein the first device is an
accessory device for the second device, and wherein the first
handshaking circuitry is located within the accessory device.
25. A method for receiving authentication with an accessory device
of a main device, the method comprising: transmitting a power
supply signal from the accessory device to the main device;
receiving a query from the main device that requests a handshake
signal from the accessory device in order to authenticate the
accessory device; transmitting a handshake signal in the power
supply signal from the accessory device to the main device; and
authenticating the handshake signal with the main device.
26. The method of claim 25, further comprising allowing the power
from the power supply signal to be used in the main device in
response to authenticating the handshake.
27. A method for using a power supply signal between a device and a
cable, the method comprising: receiving, on the device, a first
handshake signal from handshaking circuitry of the cable, wherein
the first handshake signal is provided in a power supply signal for
the device; providing a second handshake signal from the device to
the handshaking circuitry in response to the first handshake
signal, wherein the second handshake signal is provided in the
power supply signal; and changing at least one characteristic of
the power supply signal with the handshaking circuitry in response
to the second handshake signal.
28. A system comprising: first handshaking circuitry, wherein the
first handshaking circuitry is located in a first device and is
configured to: receive a power supply signal; and change a first
characteristic of the power supply signal; second handshaking
circuitry located in a second device, wherein the second
handshaking circuitry is configured to recognize the changed first
characteristic of the power supply signal; pulse generator
circuitry, wherein the pulse generator circuitry is located in the
second device and is configured to provide current spikes to the
power supply signal in response to the second handshaking circuitry
recognizing the changed first characteristic; and a current
detector, wherein the current detector is located in the first
device and is configured to recognize the current spikes, and
wherein the first handshaking circuitry is further configured to
alter a second characteristic of the power supply signal in
response to the current detector recognizing the current
spikes.
29. The system of claim 28, wherein the first handshaking circuitry
changing the first characteristic of the power supply signal
comprises stepping-down the voltage level of the power supply
signal.
30. The system of claim 28, wherein the first handshaking circuitry
altering the second characteristic of the power supply signal
comprises stepping-up the voltage of the power supply signal.
31. The system of claim 28, wherein the second handshaking
circuitry recognizing the changed first characteristic further
comprises determining that the voltage level of the power supply
signal is within a particular range for a pre-determined amount of
time.
32. The system of claim 28, wherein the first device is a cable
that is coupled to the second device, and wherein the first
handshaking circuitry is located within the cable.
33. The system of claim 32, wherein the cable comprises one or more
plugs.
34. The system of claim 33, wherein at least one of the plugs is a
Universal Serial Bus plug.
35. The system of claim 33, wherein at least one of the plugs is a
30-pin connector plug.
36. The system of claim 28, wherein the first device is a power
supply, and wherein the first handshaking circuitry is located
within the power supply.
37. The system of claim 28, wherein the first device is an
accessory device for the second device, and wherein the first
handshaking circuitry is located within the accessory device.
38. A system comprising: an accessory device, wherein the accessory
device comprises a first processor configured to: transmit a power
supply signal from the accessory device to a main device; receive a
query from the main device requesting a handshake signal in order
to authenticate the accessory device; and transmit a handshake
signal in the power supply signal to the main device; and the main
device, wherein the main device comprises a second processor
configured to: receive the handshake signal in the power supply
signal from the accessory device; and authenticate the handshake
signal.
39. The system of claim 38, wherein the second processor is further
configured to allow the power from the power supply signal to be
used in the main device in response to authenticating the handshake
signal.
40. An electronic device comprising: electrical contacts for
interfacing with another device; handshaking circuitry electrically
coupled to at least one of the electrical contacts, the handshaking
circuitry operative to: provide a power supply signal having a
first characteristic to at least one of the electrical contacts;
monitor the power supply signal for current spikes; and in response
to monitoring current spikes, provide the power supply signal
having a second characteristic.
41. A cable system comprising: a multi-region jack including at
least one electrical contact; a universal serial bus (USB) plug
electrically coupled to the multi-region jack with a cable, the USB
plug comprising handshaking circuitry operative to: provide a power
supply signal having a first characteristic to the at least one of
the electrical contacts; monitor the power supply signal for
current spikes; and in response to monitoring current spikes,
provide the power supply signal having a second characteristic.
42. The cable system of claim 41, wherein the multi-region jack is
a four region jack having a diameter of about 3.5 mm.
43. The cable system of claim 41, wherein the USB plug is a male
USB plug.
44. A system comprising: a housing designed to accommodate at least
30 contacts spaced apart in a single row of sequentially numbered
contact locations, wherein the sequentially numbered contact
locations include digital contact locations, analog contact
locations and ground contact locations; at least one electrical
contact disposed in a corresponding one of the contact locations;
handshaking circuitry electrically coupled to the at least one
electrical contact, the handshaking circuitry operative to: provide
a power supply signal having a first characteristic to the at least
one of the electrical contacts; monitor the power supply signal for
current spikes; and in response to monitoring current spikes,
provide the power supply signal having a second characteristic; and
at least one power contact for receiving power from a source
external to the system.
45. The system of claim 44 further comprising: a universal serial
bus plug including the at least one power contact.
46. The system of claim 45, wherein the handshaking circuitry is
included in the universal serial bus plug.
47. The system of claim 44 further comprising a circuit board
including the handshaking circuitry and electrically coupled to the
at least one electrical contact and the at least one power
contact.
48. The system of claim 47, wherein the housing is mounted to the
circuit board.
49. The system of claim 44, wherein the housing is a male plug
connector for connecting to a corresponding receptacle of an
electronic device.
50. The system of claim 44 further comprising: a docking station
including the housing, the at least one electrical contact, the
handshaking circuitry, and the at least one power contact.
51. A system comprising an interface for receiving a corresponding
connector of another device, the interface including at least one
electrical contact for receiving a power supply signal; handshaking
circuitry electrically coupled to the at least one electrical
contact, the handshaking circuitry operative to: recognize a power
supply signal having a first characteristic of the power supply
signal; in response to recognizing the power supply signal having
the first characteristic, introduce a validation signal to the
power supply signal; and receive the power supply signal having a
second characteristic while the validation signal is introduced to
the power supply signal.
52. The system of claim 51 further comprising: non-volatile memory;
and a processor operative to communicate with the non-volatile
memory and process one or more applications.
53. The system of claim 52 further comprising: a user input
interface for controlling one or more operations of the system.
54. The system of claim 51, wherein the interface is constructed to
receive a multi-region jack.
55. The system of claim 51, wherein the interface is designed to
accommodate at least 30 contacts spaced apart in a single row of
sequentially numbered contact locations, wherein the sequentially
numbered contact locations include digital contact locations,
analog contact locations and ground contact locations.
56. The system of claim 51, wherein the interface is a docking
connector having two sets of keying arrangement, a first-make, last
break ground contact, and a plurality of contacts arranged in a
single row, the plurality of contacts including digital and analog
contacts.
57. The system of claim 51, wherein the validation signal comprises
current spikes.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/934,733, filed Jun. 15, 2007, the disclosure of
which is incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
[0002] This invention relates to power regulation. More
particularly, this invention relates to safe power delivery.
[0003] A traditional Universal Serial Bus (USB) jack continually
provides a power supply signal at a specific voltage to any cable
connected to that USB jack via a USB plug. The electrical contacts
of a traditional USB plug, however, are protected by a protective
housing so that a user cannot accidentally touch the contacts of
the USB plug.
[0004] Not all cables operable to mate with a USB jack, however,
utilize USB plugs at each end. In fact, some cables include a
protected USB plug at one end and an unprotected plug at the other
end. Such cables are able to connect a USB device with a device
that does not have a USB jack. Such cables are deficient, however,
as a power supply signal may be provided to the unprotected plug
when the unprotected plug is not mated to a device. A person
touching an unprotected plug may be harmed as an undesirable power
supply signal may flow directly into that person's body. Such
cables are also deficient as an undesirable power supply signal may
be provided to a device even if the unprotected plug is not
properly mated with the device. A device may be severely damaged if
a power signal is provided to the wrong contacts of a device or an
undesirable power signal is provided to the correct contacts of a
device. Accordingly, it is therefore desirable to provide a cable
with improved safety measures for both human and device
interaction.
[0005] Additionally, companies occasionally try to create
accessories for devices without the permission of the manufacturers
of such devices. Such accessories are deficient, however, and may
harm the devices by providing data and power signals that can
damage the devices. It is therefore desirable to eliminate the
ability of third-party accessories to access a device in order to
protect such a device from receiving data and power signals that
may damage the device.
[0006] Traditional USB protocols include ACK (receipt of error-free
data packet), NAK (receiving device cannot accept data), STALL (end
is postponed), and NYET (no response yet). Such protocols are
deficient, however, as such protocols do not provide enhanced
functionality. It is therefore desirable to provide circuitry with
an enhanced range of communication capabilities and device
functionality.
SUMMARY OF THE INVENTION
[0007] Handshaking circuits are provided that can identify one
another using a power supply signal. Such handshaking circuits can
also control the characteristics of the power supply signal so that
a desirable power supply signal is delivered at a desirable time.
Such handshaking circuits may, for example, regulate the voltage or
current of a power supply signal as well as embed information into
a power supply signal by manipulating the voltage or current of a
power supply signal. Accordingly, handshaking circuitry is provided
that allows devices to identify one another through a signal (e.g.,
a power supply signal) as well as communicate additional (e.g.,
power supply control information).
[0008] Handshaking circuits may receive information embedded in the
power supply signal from each other and may, in turn, utilize the
received information to perform different types of operations. For
example, a handshaking circuit may change the voltage of a power
supply signal being supplied to a different handshaking circuit
based on information received from this different handshaking
circuit. For example, a handshaking circuit may introduce pulses of
current into a power supply signal that the handshaking circuit
receives. Such current pulses may be detectable and identifiable by
the circuitry providing the power supply signal. Information sent
to a circuit providing a power supply signal may instruct the
circuit to, for example, increase or decrease the voltage of the
power supply signal to a particular amount. Such information may
alternatively, for example, instruct the circuit providing the
power supply signal at a particular voltage to continue providing
the power signal at that particular voltage.
[0009] A handshaking circuit may be provided in a cable having a
power supply line. In doing so, the cable can modify the
characteristics of any power supply signal provided through the
cable independent of any device connected to the cable. A
handshaking circuit may be provided on any portion of a cable. For
example, a handshaking circuit may be provided as a flexible
integrated circuit located in a part of the body or plugs of the
cable. Accordingly, an on-cable handshaking circuit is
provided.
[0010] A handshaking circuit may be provided in a device such as a
portable device. The on-device handshaking circuit may interact
with an on-cable handshaking circuit to make sure that the device
is provided with a desired power supply signal at a desired time.
In addition to power, data may also be provided through the cable
and the handshaking circuit may, or may not, control or manipulate
the flow of data through the cable's data channels. For example,
one device that includes a handshaking circuit may take the form of
a portable music player. The on-cable and on-device handshaking
circuits may be utilized to make sure a power supply signal is
being properly supplied to the device before the primary circuitry
of the device is allowed to connect to the cable and receive the
data portion (e.g., music data) of the communication.
[0011] A cable is provided that includes a USB plug at one end and
an unprotected, multiple-region plug at the other end. A
handshaking circuit is provided in the cable. Another handshaking
circuit is provided in a portable device. The on-cable handshaking
circuit may receive a relatively HIGH power signal (e.g., 5
volts@500 mA) and may step the voltage of this relatively HIGH
power signal down to a particular, relatively LOW power signal
(e.g., a current-limited 2.9 volts). The on-device handshaking
circuit may be configured to look for a characteristic of this
particular, relatively LOW power signal such as, for example, the
voltage of this power supply signal. Once this particular,
relatively LOW power signal is recognized for a particular period
of time (e.g., 0.5 seconds), the on-device handshaking circuit may
introduce current pulses into the power supply signal that the
on-device handshaking circuit is receiving from the on-cable
handshaking circuit. These current pulses may then, in turn, be
recognized by the on-cable handshaking circuit providing the power
supply signal. The current pulses provided by the on-device
handshaking circuit may, for example, communicate control
information to the on-cable handshaking circuit. For example, the
current pulses may instruct the on-cable handshaking circuit that
the on-device handshaking circuit desires to receive a HIGH power
signal instead of a LOW power signal. Thus, for example, once the
on-cable handshaking circuit recognizes the current pulses, the
on-cable handshaking circuit may step the particular, relatively
LOW power signal (e.g., a current-limited 2.9 volts) up to a
relatively HIGH power signal (e.g., 5 volts@500 mA).
[0012] Handshaking circuits may provide, for example, two
handshaking steps. In the first handshaking step, for example, the
on-cable handshaking circuit may identify itself by sending a
particular voltage, continuously, for at least a particular amount
of time. The first handshaking step may complete when the on-device
handshaking circuit recognizes that the particular voltage was sent
for at least the particular amount of time. In the second
handshaking step, the on-device handshaking circuit may identify
itself by introducing current spikes into the power supply signal.
The second handshaking step may complete when the on-cable
handshaking circuit recognizes the current spikes from the
on-device handshaking circuit. Different types of current spikes
can be sent from the on-device handshaking circuit to instruct the
on-cable handshaking circuit to perform different types of
operations. Similarly, for example, different (e.g.,
pre-determined) voltages may be sent from the on-cable handshaking
circuit to instruct the on-device handshaking circuit to perform
different types of information. Additional handshaking steps may be
included as part of an overall handshaking routine.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The above and other objects and advantages of the present
invention will be apparent upon consideration of the following
detailed description, taken in conjunction with accompanying
drawings, in which like reference characters refer to like parts
throughout, and in which:
[0014] FIG. 1 is an illustration of a data and power delivery
topology constructed in accordance with an embodiment of the
present invention;
[0015] FIG. 1A is an illustration of a power delivery topology
constructed in accordance with an embodiment of the present
invention;
[0016] FIG. 2 is an illustration of a data and power delivery
topology including on-cable and on-device handshaking circuits
constructed in accordance with an embodiment of the present
invention;
[0017] FIG. 3 is an illustration of process flow charts constructed
in accordance with an embodiment of the present invention; and
[0018] FIGS. 4 and 5 are schematics of handshaking circuits
constructed in accordance with an embodiment of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0019] FIG. 1 shows topology 100 that may include device 101 and
device 103 that are electrically coupled together via cable
102.
[0020] Device 101 and device 103 may be coupled together so that,
for example, data and/or power may be transferred between devices
101 and 103. Devices 101 and 103 may be any type of devices such
as, for example, portable laptops, stationary personal computers,
telephonic devices, audio/video playback devices, accessories, or
any other type of device. For example, device 101 may be a computer
while device 103 may be an audio playback device such as, for
example an iPod.TM. (available from Apple Inc. of Cupertino,
Calif.). As such, device 101 may utilize cable 102 to power and
recharge device 103 while transferring audio data to device
103.
[0021] Cable 102 may be, for example, a USB cable. Such a USB cable
may be utilized to provide a power signal from one device (e.g., a
laptop) to another device (e.g., an accessory or portable
electronic device). Accordingly, an on-cable handshaking circuit
may step-down the power signal supplied by the device (e.g., a
laptop) to a portable electronic device, wait to recognize the
appropriate current spikes provided by an accessory, and step-up
the voltage to an appropriate level in response to the appropriate
current spikes. In doing so, for example, only authorized devices
may be able to utilize a USB cable having an on-cable handshaking
circuit. Unrecognized devices may not have the capability, for
example, of sending the appropriate current spikes that are
identifiable by the on-cable handshaking circuit. Accordingly,
on-cable (e.g., on-USB cable) and on-device (e.g., on-portable
electronic device) handshaking circuitry may be provided to ensure
that only authorized devices have the capability of properly mating
and operating with each other.
[0022] Persons skilled in the art will appreciate that a device may
receive too much power through a cable (e.g., a USB cable), receive
an improperly regulated power supply signal through a cable, or
otherwise be exposed to a potentially harmful power supply signal.
Accordingly, handshaking circuits may be included in cables and
devices so that a device may identify and authenticate a cable
through the handshaking circuitry prior to utilizing a power supply
signal. Similarly, a device can be protected from an accessory that
could damage a device's power regulation and transmission
circuitry.
[0023] Alternatively, the handshaking circuitry in a cable may
lower the power supply signal for a particular device based on
identification current pulses provided by that device. In doing so,
for example, the cable may step a voltage down to an appropriate
level in response to proper identification current spikes that are
associated with such a regulation scheme. In this manner, a power
supply signal may be changed to a predetermined value based on the
handshake received.
[0024] An on-cable handshaking circuitry may include, for example,
on-cable memory that includes a table that associates particular
types of current spikes to particular actions. Such a table, for
example, may include data associated with how an on-cable
handshaking circuit should operate when connected to different
accessories or portable electronic devices.
[0025] FIG. 1A illustrates an example of two devices each having
handshaking circuits in accordance with an embodiment of the
invention. As shown, power providing device 140 includes a
handshaking circuitry 142 (e.g., circuitry 500 of FIG. 5) may be
provided in a device providing a power signal. Power providing
device 140 may receive power from external power source 160 (e.g.,
wall outlet, battery, etc.) and regulate how power is provided to
power receiving device 150, which includes handshaking circuitry
152 (e.g., circuitry 400 of FIG. 4). Device 140 and device 150 may
be directly coupled together via interfaces 144 and 154, or devices
140 and 150 may be connected with a cable having the appropriate
connectors to mate with interfaces 144 and 154, though the cable,
including its connectors, may not have any handshaking circuitry.
For example, device 140 may be any suitable device such as an
accessory (e.g., wall mounted charger, a car charger, docking
station, speaker docking system) or a computer, and device 150 may
be a portable electronic device such as an iPod or iPhone.
Interfaces 144 and 154 may be proprietary multi-contact connectors
(e.g., a 30-pin connector) a USB connectors, Firewire connectors,
3.5 or 2.5 mm jack connectors, a combination thereof, or any other
suitable connector.
[0026] In order to protect device 103 from, for example, receiving
an undesirable power supply signal, handshaking circuitry may be
provided to make sure the appropriate power supply signal is
supplied to device 103 at the appropriate time. Handshaking
circuitry may also, for example, allow devices to identify each
other such that devices without a handshaking circuit cannot be
utilized.
[0027] A handshaking protocol may include any number of stages. For
example, a handshaking protocol may be initiated by an initiating
handshaking circuit providing a power supply signal. This
initiating handshaking circuit may, for example, change a
characteristic of the power supply signal in a particular manner.
For example, the initiating handshaking circuit may decrease the
voltage of the power supply signal to a particular amount that a
responding handshaking circuit may expect to see in place of the
increased, primary power supply signal.
[0028] A responding handshaking circuit may receive a power supply
signal and may determine whether a characteristic of the power
supply signal is within a particular range. For example, the
responding handshaking circuit may determine whether the voltage of
the power supply signal is within a particular range. Such a
voltage range may be, for example, based off the voltage that an
initiating handshaking circuit would provide during a handshaking
routine (e.g., 2.9 volts) and a margin of error (e.g., +0.2 volts
and -0.2 volts). If, for example, the responding handshaking
circuitry receives a power supply signal with a voltage in this
voltage range, the responding handshaking circuitry may wait a
particular amount of time (e.g., 0.5 seconds) in order to confirm
that the voltage of power supply signal is steady. Once the time
requirement of the handshaking routine has been met, the responding
handshaking circuitry may manipulate the power supply signal in a
manner that is detectable by the initiating handshaking circuitry.
For example, current pulses may be introduced into the power supply
signal that may be detected by the initiating handshaking
circuitry. Once the initiating handshaking circuitry detects such
current pulses, the initiating handshaking circuitry may, for
example, change a characteristic of the power supply signal.
Particularly, for example, the initiating handshaking circuitry may
increase the voltage of the power supply signal to a power supply
signal for powering and recharging a particular device.
[0029] Persons skilled in the art will appreciate that if, for
example, the responding handshaking circuit does not receive a
voltage within the expected range, the handshaking circuit may not
forward the power supply signal to other circuitry such as the
primary circuitry of a device. Alternatively, for example, the
primary circuitry of a device may not allow a power supply signal
to power the primary circuitry if a characteristic of the power
supply signal does not meet a threshold. For example the primary
circuitry of a device may not utilize a power supply signal
received from a handshaking circuit if the voltage of the power
supply signal does not exceed a pre-determined voltage (e.g., 4.5
volts).
[0030] A handshaking circuit may be dedicated to an initiating or
responding functionality. Alternatively, a handshaking circuit can
include both an initiating and responding functionality.
Alternatively still, a handshaking circuit may be fabricated with
both an initiating and responding functionality, but only one of
these functionalities may be enabled during manufacturing or
distribution. Additionally, any portion of a handshaking device may
be embodied in hardware (e.g., analog and/or digital circuitry)
and/or software. For example, a handshaking device may be
fabricated as a flexible integrated circuit.
[0031] Persons skilled in the art will appreciate that a
handshaking protocol may be performed over a data line instead of a
power supply line. Similarly, a data line may not be affected by a
handshaking protocol over a power line or transmission through a
data line may be controlled/stopped by a handshaking protocol.
[0032] Cable 102 may be any type of cable such as, for example, a
wire-based cable or an optical cable. Similarly, cable 102 may
include a plug at each end. Such plugs may be of the same type or
different types of plugs. For example, the plugs of cable 102 may
be USB plugs. As per another example, one plug of cable 102 may be
a USB plug while another plug of cable 102 may be a multiple region
vertical plug (e.g., a four region vertical plug). Persons skilled
in the art will appreciate that a cable may have more than two
plugs. For example, a cable may have one primary USB plug and the
cable from this plug may split off into multiple plugs (e.g., a
microphone plug, a FireWire plug, a USB 2.0 plug, an A/V plug, a
component plug, an HDMI plug). As per another example, an end of a
cable may be open in such a manner that this end does not contain a
plug, but allows direct access to the internal channels of the
cable. Cable 102 may include any number of power and/or data
channels.
[0033] Cable 102 may be, for example, cable 110 that includes a
protected, USB plug 111 that can couple to USB jack 112. Cable 110
may also include a multiple-region vertical male plug that can
couple to a multiple-region vertical female jack. The
multiple-region plug may include multiple contacts for the delivery
of power and data signals. For example, the multiple-region plug
may be a four-region plug. Contact 121 may be a power supply
contact. Contact 122 may be a ground contact. Channel 123 may be a
data contact. Contact 124 may be another data contact. The
four-region plug may be operable to couple to an associated
four-region jack. The four-region plug may be considered a vertical
plug in that at least one contact on the plug has to pass by an
unrelated contact on a jack in order for that contact to
electrically couple to the correct contact on the jack. For
example, contact 124 has to pass contacts 131, 132, and 133 in
order to electrically contact with channel 134. As such, contacts
on a vertical plug may regularly couple with unwanted contacts on
an associated jack while the plug is mechanically mating with the
jack.
[0034] FIG. 2 shows various handshaking circuit topologies 200. For
example, plug 210 may include handshaking circuit 211 that can
communicate with handshaking circuit 270 of device 250. In this
manner, plug 210 may include an on-plug handshaking circuit while
device 250 includes an on-device handshaking circuit. Handshaking
circuit 270 may communicate with, for example, circuitry 260.
Memory 261 and/or processor 262 may be included in circuitry
260.
[0035] An on-cable handshaking circuit may be provided on any
portion of a cable. For example, cable 220 provides handshaking
circuit 240 on a plug other than a plug operable to couple to jack
280 of device 250 so that cable 220 may also include a plug without
handshaking circuit 240 that is operable to couple to jack 280 of
device 250. In doing so, for example, cable 220 may couple to jack
280 of device 250 with a plug that does not include a handshaking
circuit, while having a plug that does include a handshaking
circuit so that a handshaking process may still be performed. As
another example, handshaking circuit 240 may be provided on the
body of a cable instead of the plug of a cable (e.g., as in
handshaking circuit 231 of cable 230). In yet another example,
cable 290 may be provided that includes a plug without handshaking
circuit 240 that splits into two different plugs that each include
a handshaking circuit (e.g., handshaking circuits 291 and 292). In
providing multiple plugs with different handshaking circuits, a
device may be able to identify each plug separately as the
handshaking circuits may operate differently (e.g., provide a
different initial handshake voltage).
[0036] Persons skilled in the art will appreciate that a cable may
include any number of plugs and that such plugs may be of varying
types. In this manner, for example, one end of a plug may be a
wireless receiver/transmitter for wirelessly receiving/transmitting
communications signals such as handshaking signals.
[0037] A plug may be, for example, a multiple-pin connection plug
such as 30-pin connection plug 242. One example of a 30-pin
connection plug is described in Fadell et al. U.S. Patent
Publication No. 2004/0224638, which is hereby incorporated by
reference herein in its entirety. Further discussion of a 30-pin
connection plug can be found in U.S. Pat. No. 7,293,122, which is
hereby incorporated by reference in its entirety. The 30-pin
connecter may exist in male and female form. The female form of the
30-pin connector typically resides inside a portable electronic
device. In some embodiments, the female 30-pin connector can have a
keying structure to guide a counterpart male connector therein,
first mate, last break ground contact pins, and several pins
arranged in a row, in sequential order.
[0038] The male form of the 30-pin connector is typically included
with accessories such as docking stations, speaker systems, cables,
car chargers, or any other suitable device, some of which may be
capable of receiving power from an external power source. The
accessories typically include a circuit board to which the 30-pin
connector is mounted. The 30-pin connector may include a housing
designed to accommodate at least 30 contacts spaced apart in a
single row of sequentially numbered contact locations, the
sequentially numbered contact locations including digital contact
locations, analog contact locations and ground contact locations.
The contact locations may be selectively populated with one or more
electrical contacts. The male 30-pin may also include a keying
structure. In some embodiments, handshaking circuitry (e.g.,
on-cable handshaking circuitry) may be included in the accessory
and is electrically coupled to at least one of the electrical
contacts.
[0039] As mentioned above, persons skilled in the art will
appreciate that a cable may include any number of plugs and that
such plugs may be of varying types. For example, one end of cable
240 can be 30-pin connection plug 242 and another end can be USB
plug 241. In this manner, handshaking circuitry 243 can be located
in one or more of cable 240, 30-pin connection plug 242, and USB
plug 241.
[0040] Persons skilled in the art will also appreciate that a
device that is providing power to a second device may be coupled
via a cable that includes two handshaking circuits. Handshaking
circuits may, for example, be included in both the device that is
providing a power signal and the device that is receiving a power
signal. Accordingly, the cable may be able to identify the devices
that are coupled to the cable via the varying handshaking circuits.
In this manner, the cable may become aware of its operational
environment and may change its own operation autonomously. For
example, the cable may include a microprocessor, memory, and source
of power such as a battery. The cable may be programmed to provide
different functionalities depending on the operating environment.
For example, suppose a user has a secure laptop that includes a
handshaking circuit operable to provide a specific identification
for that laptop. Accordingly, suppose a user requires the use of a
secure accessory such as a secure backup memory device. This secure
backup memory device may include a handshaking circuit that may be
able to provide a specific identification for that memory device.
Thus, a cable may be issued to a user that allows, for example, one
or more signals to be transferred through the cable so long as the
specific laptop and specific storage device are used. Accordingly,
an administrator may program a cable with information indicative of
different device identities and how the cable should operate once
an operational environment is recognized. Utilizing the above
example, suppose the secure storage device is connected, via the
programmed cable, to a laptop other than the secure laptop.
Accordingly, the cable may not allow signals, such as a power
supply signal) to be provided to the secure storage device as the
cable may recognize that the laptop as not being the secure laptop.
Such a scheme provides, for example, increased security.
[0041] Persons skilled in the art will appreciate that if a cable
includes, for example, a rechargeable source of power that such a
rechargeable source of power may be recharged while the cable is
provided with a power signal. Cables with handshaking circuits may
be utilized to subvert unlicensed third-party accessories from
damaging devices. Handshaking circuits may be used to identify, or
may be provided in, any type of accessory and may be utilized to
identify any specific accessory for any type of accessory. Such
accessories may include, for example, headphones, portable media
devices, speaker systems, microphones, storage devices, projectors,
docking stations, display systems, radio systems, wireless
communications systems, or any other device. Such accessories may
be, for example, powered eternally or may receive power to operate
from a parent device.
[0042] Persons skilled in the art will appreciate that a device
that receives power from a device in one mode may provide power to
a different device in another mode. For example, a portable media
player may receive power from a personal computer (e.g., a laptop)
through a cable. But, for example, that portable media player may
then provide power to a device via the same, or different, cable.
Accordingly, the handshaking circuits of the cable and/or the
handshaking circuits of the associated devices may be made aware of
the operational environment the cable and devices are operating in.
Additionally, a portable media device may be subordinate to, and an
accessory of, a laptop, but that portable media device may be a
mated to a microphone and speaker headset. A portable media player
may, for example, utilize an accessory device, such as a docking
station, and handshaking circuits may be provided in the docking
station, portable media device, and/or the associated cable. A
30-pin connector may be used to couple the two devices together via
a plug. Accordingly, for example, the portable media device may be
required to send a handshaking signal to the docking station before
the docking station may receive signals from the portable music
device (or vise versa). Such signals may include, for example,
media information signals, control signals for either device,
appropriate ground signals, power signals, or any other type of
signal. For example, before transmitting power to a portable
electronic device, the portable electronic device may require a
suitable handshake from the accessory. As per another example, a
device may require a suitable handshake from an accessory before
transferring data (e.g., accepting a transfer of data).
Accordingly, an authentication method is provided that may assist
to ensure the safe transfer of power and/or data between a main
device (e.g., via a handshaking circuit on device 103 of FIG. 1)
and an accessory (e.g., handshaking circuit 106 of device 105 of
FIG. 1 that, for example, can be coupled to device 103 through
cable 107) and helps prevent unsuitable accessory devices from
accidentally or intentionally harming the main device or associated
user.
[0043] Handshaking circuitry may be included in a power supply or
power adapter for a device. For example, handshaking circuitry 109
of FIG. 1 may be provided in wall power plug 108 of FIG. 1 and the
handshaking circuitry 109 of plug 108 of FIG. 1 may perform a
suitable handshake to a wall socket having a handshaking
device.
[0044] A power adapter may be coupled between a device and an
external or portable power supply. Such power adapters and power
supplies may include handshaking circuitry. Such a power supply may
include, for example, a battery, wall-socket, or cigarette lighter.
A power adapter may be located on a power cord that is connecting a
device to an external power supply. Accordingly, for example, when
handshaking circuitry is located in a power supply or power
adapter, the device may require that the power supply (or power
adapter) send a handshaking signal prior to the device accepting
power from the power supply.
[0045] FIG. 3 shows flow charts 310, 320, 330, and 340, each of
which includes a number of steps. Persons skilled in the art will
appreciate that a flow chart may include additional steps, fewer
steps, modified steps, and/or the order of the steps may be
re-arranged. Flow chart 310 may initiate at step 311 when a
handshaking circuit receives primary power in the form of a power
supply signal. Such a handshaking circuit may step down the voltage
of the power supply signal in step 312 to provide protected power
to a device in step 313. The handshaking circuit may then wait
until information is received back from the device in step 314.
Such information may take the form of current pulses in the
protected power provided to the device. In response to receiving
the appropriate information, the handshaking circuit may step-up
the protected power to a primary power voltage. The handshaking
circuit may step-up the protected power by providing the primary
power that the handshaking circuit receives to the device in step
315. Persons skilled in the art will appreciate that the source of
primary power may be a DC signal from a battery, such as a battery
concurrently powering a laptop, or an AC power signal from a wall
outlet.
[0046] Flow chart 320 may initiate when, for example, a handshaking
circuit receives a power supply signal in step 321. The handshaking
circuit determines whether or not the received power supply signal
is within a particular range in step 322. A power signal may be
within a particular range, for example, if a characteristic of the
power signal is within a particular range. For example, step 322
may determine whether the voltage of the power supply signal
received by the handshaking circuit is within a particular range of
voltages. Alternatively, for example, step 322 may determine
whether a characteristic, such as voltage, is above or below a
particular threshold. Step 322 may also determine whether the
detected condition persists for a period of time. Once the
conditions of step 322 are met, step 323 may initiate, in which
characteristics of the power supply signal are changed in such a
manner that the device providing the power supply signal can detect
the changed characteristics. Thus, for example, step 323 may change
the current of the power supply signal by introducing current
pulses in the signal that are detectable at the device supplying
power to the handshaking circuit. Once the pulses are generated and
detected by the device, the device may couple the power supply
signal to primary circuitry of the device in step 324. A
determination as to whether the power supply signal exceeds a
particular voltage or is within a particular range may be included
in step 324 to ensure that a handshaking circuit at the device
supplying the power supply signal has recognized the reception of
the current pulses. Primary circuitry of a device may include
circuitry to only allow a supply voltage signal having particular
characteristics (e.g., an appropriate voltage) to connect to the
primary circuitry (e.g., step 325).
[0047] Persons skilled in the art will appreciate that once a
handshaking circuit in a device finishes the handshaking process
and begins to receive a power supply signal appropriate to power
the device, the handshaking circuit may continue to manipulate the
protected power supply signal in the same manner the handshaking
circuit did to receive the appropriate power supply signal. In
other words, the handshaking circuit may continue to introduce
current pulses into the power supply signal the entire time the
device is receiving the power supply signal. In doing so, the
initiating handshaking circuit that provides the power supply
signal may be able to continually recognize that the responding
handshaking circuit is electrically coupled to the initiating
handshaking circuit. In the event that the two handshaking circuits
are disconnected, the initiating handshaking circuit may realize
the disconnection by recognizing the absence of the current pulses
(or any information provided by a device connected to the
initiating handshaking circuit). In doing so, the initiating
handshaking circuit may realize that the initiating handshaking
circuit should step the voltage of the supplied power signal down
to an appropriate, protected power supply signal.
[0048] A responding handshaking circuit may continue sending
current pulses across a power supply signal even after the voltage
of the power supply signal is stepped-up to a level outside of the
voltage range required to initiate the introduction of the current
pulses to the power supply signal. In this manner, the responding
handshaking circuit may continue to provide information to an
initiating handshaking circuit such that the initiating handshaking
circuit knows that the device is still connected. Persons skilled
in the art will appreciate that disconnection may be determined in
a variety of ways. For example, the interruption of data being
communicated between two devices may be utilized as an indication
of disconnection and may initiate a new handshaking routine. When a
new handshaking routine is initiated, for example, the voltage
(and/or current) of the power supply signal provided by the
initiating handshaking circuit may be stepped down to a
predetermined level.
[0049] Flow chart 330 may be utilized, for example, as part of a
handshaking protocol between two devices. For example, flow chart
330 may be utilized as part of an on-cable to on-device handshaking
protocol over a power supply signal. Flow chart 330 may include
step 331, in which a characteristic if a power supply signal is
analyzed. Accordingly, for example, step 331 may analyze the
voltage of a power supply signal to determine if the voltage is
above (or below) a particular threshold (e.g., 2.7 volts). Once the
voltage of the power supply signal is determined to be within a
particular range, the power supply signal may be provided to timing
circuitry in step 332. Next, the circuitry may determine whether a
characteristic of the power supply signal is below (or above) a
particular threshold. Accordingly, for example, step 333 may
determine whether the voltage of the power supply signal is below a
particular threshold (e.g., 3.1 volts). Persons skilled in the arts
will appreciate that by first determining whether a voltage is
above a threshold and then determining whether a voltage is below a
different threshold (or vise versa) that a determination may be
made as to whether a voltage is within a particular range. Such a
voltage range may be of any size. Preferably, the voltage range
does not include a voltage intended to be a primary power supply
signal (e.g., 5 volts) and preferably the range is widened to take
into account an expected margin of error for the particular
environment. Once the characteristic (e.g., voltage) is determined
to be within a particular range, a counting circuit may be started
in step 334.
[0050] Such a counting circuit may count up based on the speed of a
clock signal that drives the counting circuit. This counting
circuit may, for example, be coupled to locking circuitry that may
lock the counter at a particular value once it is reached. A single
output bit, or any number of output bits, from the counter may be
utilized as a control signal. For example, once a counter reaches
128, the seventh bit (i.e., the most significant bit) may change
from a logic "0" to a logic "1." The locking circuitry may be
utilized to hold the value of the counter once this bit changes to
a logic "1" and may be utilized to determine when a characteristic
(e.g., the voltage) of the power supply signal has remained within
a particular voltage range for a particular period of time. Persons
skilled in the art will appreciate that the dynamics of the
counting circuit and/or clock may be changed so that a particular
count (e.g., 128) reflects a particular amount of time (e.g., 1/2
second).
[0051] Step 335 may be initiated once the counting circuit reaches
a particular count. In step 335, a characteristic (e.g., the
current) of the power supply signal may be changed such that the
device sending the power supply signal can recognize that an
appropriate device has received the power supply signal for at
least a particular period of time. Such a device may then change a
characteristic of the power supply voltage. For example, such a
device may increase the power supply voltage from a safe, protected
voltage level utilized for identification to a voltage level
utilized for powering a device. Persons skilled in the art will
appreciate that a safe, protected voltage level may be a voltage
level that is unlikely to cause bodily harm or pain. Such a safe,
protected voltage level may also be unlikely to cause damage to a
circuit not intended to receive the increased voltage level.
[0052] Flow chart 340 may be utilized to discern between different
types of devices that may be utilized through a common plug and
jack interface. Step 341 may occur, for example, when two
handshaking circuits communicate with each other via a power supply
signal. Once step 341 completes, the devices that the handshaking
circuits are trying to protect may be able transfer both power and
data. For example, a laptop may transfer music data to a portable
music player in step 342 while simultaneously supplying a power
supply signal to the portable music player in order to recharge the
battery of the portable music player. The handshaking circuits may
then be disconnected by removing the cable connecting two
handshaking circuits.
[0053] A different device, one without a handshaking circuit, may
then be placed in the plug and may still be utilized by the
portable music player in step 343. For example, headphones or
speakers may be connected to the plug in step 343. Here, the
portable device may provide, for example, analog music signals to
the plug and may turn the handshaking circuit OFF or not utilize a
handshaking circuit in order to deliver such a signal. Persons
skilled in the art will appreciate that headphones and/or speakers
may provide information to a device to which the headphones and/or
speakers are connected. For example, a volume control signal may be
provided back through a plug supplying music signals, such as
analog or digital music signals, to the headphones and/or
speakers.
[0054] Yet another type of device may be connected to the plug in
344. For example, a microphone may be placed in the plug through
344. Such a device may or may not include a handshaking circuit.
For example, a microphone may provide signals to a power supply
signal contact that is not within a range of any handshaking
circuit or a primary power supply signal. Accordingly, a
handshaking circuit within a device receiving a microphone signal
may recognize such a voltage and, in doing so, may recognize that a
microphone is connected to a plug. As such, the handshaking circuit
may allow the device to utilize the plug as a microphone plug and,
for example, receive an analog microphone signal in step 345. As
shown above, a device with a handshaking circuit and a single plug
may utilize the same plug for a number of different types of
devices that require different types of interaction with the
plug.
[0055] FIG. 4 shows handshaking circuit 400 that may, for example,
communicate with another handshaking circuit through a power signal
and, in doing so, provide the supplier of the power signal with
instructions on how to provide the power signal in the future. For
example, handshaking circuit 400 may protect a device from
receiving relatively HIGH voltages before the device is ready to
receive such HIGH voltages. Handshaking circuit 400 may, for
example, be included in a device receiving a power signal and the
device supplying the power signal may include another handshaking
circuit.
[0056] Persons skilled in the art will appreciate that a device
and/or cable may include two handshaking circuits where one
handshaking circuit is utilized when supplying power and the other
handshaking device is utilized when receiving power. Alternatively,
for example, a handshaking circuit may be provided that includes
the ability to perform both the initiating steps of a handshake
(e.g., by varying a supply voltage to a predetermined level) and
the responding handshake (e.g., by supplying the appropriate
current pulses). In doing so, for example, a device (e.g., a
portable media device) may be able to communicate both with a power
supplying device providing power (e.g., a laptop) to a rechargeable
battery located on the device and an accessory (e.g., a
microphone/speaker accessory) in need of power. Accordingly, for
example, the inclusion of both functionalities allows a device to
communicate with power supply devices and devices needing power
through a common jack such as a microphone jack or a 30-pin
connector.
[0057] Handshaking circuit 400 may determine whether a power supply
signal is within a particular voltage range for a period of time.
If so, handshaking circuit 400 may manipulate the current of the
power supply signal, by introducing identifiable current pulses
into the power supply signal, to instruct the provider of the power
supply signal to perform an operation. For example, the provider of
the power supply signal may recognize the current pulses and
step-up the voltage of the power supply signal from a relatively
LOW voltage (e.g., 2.9 volts) to a relatively HIGH voltage (e.g., 5
volts).
[0058] Handshaking circuit 400 may include input node 491 that is
electrically coupled to a power contact of an input/output jack.
When the input/output plug of a device properly mates with such an
input/output jack, a power supply signal may be received on node
491 from the device.
[0059] Voltage detection circuitry 410 may be included in
handshaking circuit 400. Voltage detection circuitry 410 may
utilize voltage detector 411 to determine whether the voltage of
the power supply signal on node 491 meets a particular threshold.
For example, voltage detector 411 may determine whether the voltage
of the power supply signal on node 491 is above a particular
threshold (e.g., 2.7 volts). If the threshold is met, voltage
detector 411 may provide a signal to turn switch 413 ON. Persons
skilled in the art will appreciate that some voltage detectors
(e.g., comparators) may provide a signal that does not have the
correct polarity to turn ON some switching circuits (e.g.,
transistors). In such instances, for example, inverting circuit 412
may be provided to invert the polarity of the signal that is
provided by voltage detector 411 to turn switch 413 ON.
[0060] Once switch 413 turns ON, switch 413 may allow the power
supply signal on node 491 to flow to node 492. Oscillator circuit
420 may be included in handshaking circuit 400. Oscillator circuit
420 may be, for example, a low-powered oscillator circuit that runs
at a steady frequency over time (e.g., 200 Hz). Oscillator circuit
420 may be configured, for example, to run only when a power supply
voltage is provided to node 492 via switch 413. Particularly, node
492 may provide a power signal to oscillator 421. The output of
oscillator 421 of oscillator circuit 420 may be provided to a logic
gate, such as NOR gate 441.
[0061] In this manner, a power supply voltage can be stepped down
to provide a handshaking functionality, yet still provide
sufficient power to power the circuitry of a handshaking device.
Accordingly, a device having a handshaking circuit may have a
battery that is completely drained of power, yet a handshaking
circuit of a device may be powered even if a power supply voltage
is stepped down for handshaking purposes.
[0062] The power supply signal provided to node 492 via switch 413
may also be provided to voltage detector 431. Voltage detector 431
may determine whether the voltage of the power supply signal
provided to node 492 meets a particular threshold. For example,
voltage detector 431 may determine whether the voltage of the power
supply signal falls below a particular threshold (e.g., 3.1 volts).
Persons skilled in the art will appreciate that voltage detectors
411 and 431 may, when utilized together, determine whether a
voltage of the power supply signal falls within a pre-determined
range of voltages (e.g., 2.7 volts to 3.1 volts). Such a range may
take into account a margin of error for a particular environment.
For example, if handshaking circuit 400 expects to receive a power
supply signal having a voltage of 2.9 volts, yet a margin of error
is determined to be 0.2 volts, the handshaking circuit can widen
the expected voltage (2.9 volts) to include the margin of error
(e.g., 2.7 volts to 3.1 volts).
[0063] The output of voltage detector 431 may be provided, for
example, to the same logic gate that received the output of
oscillator circuit 420. For example, the outputs of voltage
detector 431 and 420 may be provided to NOR gate 441.
[0064] NOR gate 441 may have any number of inputs (e.g., three). As
gate 441 has a NOR functionality, the output of NOR gate 441 may
turn LOW whenever any of the inputs to the NOR gate is HIGH.
Persons skilled in the art will appreciate that voltage detector
431 may be configured, or may be coupled to circuitry, such that if
the threshold of voltage detector 431 is met, a LOW signal may be
provided to NOR gate 441. Accordingly, NOR gate 441 may clock
counter 451 at the frequency of oscillator 421 so long as the
threshold of voltage detector 431 is met.
[0065] Persons skilled in the art will also appreciate that node
493 may be configured to initially provide a LOW signal to NOR gate
441 such that counter 451 may be enabled. Particularly, node 493
may be electrically coupled to an output bit of counter 451 (e.g.,
the seventh most significant output bit of counter 451).
Accordingly, counter 451 may initiate with an initial count of 0.
As such, every output bit of counter 451 may include a LOW signal
(e.g., 0 volts or a logic "0" voltage signal).
[0066] So long as voltage detector 441 provides a LOW signal (e.g.,
the threshold of voltage detector 441 is met), NOR gate will cause
counter 451 to count up from a starting value (e.g., 0) at the rate
of oscillator 421. As counter 451 counts up, the output bits of
counter 451 may start to change states. For example, when counter
451 counts from 0 to 1, the least significant output bit may change
from a LOW signal to a HIGH signal. Accordingly, counter 451 may be
utilized to count to any value and, as a result, counter 451 may be
utilized to count any amount of time. For example, counter 451 may
be configured such that the counter reaches 128 (e.g., the seventh
most significant bit is changed from a LOW signal to a HIGH signal)
after a pre-determined amount of time (e.g., 0.6 seconds). Such an
output bit may be utilized as the input to NOR gate 441 such that
the output of NOR gate 441 switches from HIGH to LOW when counter
451 reaches a count of 128. In doing so, counter 451 is instructed
to stop counting, as pulses from oscillator 421 are no longer
passed onto counter 451, and counter 451 will hold (e.g., latch
onto) the last counted value (e.g., 128). In turn, the output bit
utilized to switch NOR gate 441 OFF may also remain constant.
Accordingly, this output bit may be utilized to provide control
signals to additional components of handshaking circuit 400 via
node 493.
[0067] Node 493 may be utilized, for example, to turn switch 461 ON
once counter 451 measures a predetermined amount of time. Switch
461 may, in turn, cause switch 481 to turn ON. For example, switch
461 may electrically couple a gate terminal of switch 481 to ground
in order to turn switch 481 ON.
[0068] Persons skilled in the art will appreciate that the primary
circuitry of a device (e.g., a portable music player) may be
coupled to node 494. Such primary circuitry may include a voltage
detector to determine whether the voltage being supplied to the
primary circuitry is primary power supply signal (e.g., 5 volts) by
including a voltage detector to detect whether the received power
supply signal is adequate (e.g., above 4.5 volts).
[0069] In turning switch 481 ON, the power supply signal on node
491 is provided to pulse generator circuit 470. Pulse generator
circuit 470 operates as follows. When switch 471 is turned ON, the
power supply voltage at node 494 dissipates over resistor 472 into
ground 499 via switch 471. In doing so, resistor 472 creates
current pulses in the power supply signal at the switching rate of
oscillator 421.
[0070] Person skilled in the art will appreciate that a handshaking
circuit may utilize both power leads (e.g., a power contact and a
ground contact) in order to provide a handshaking functionality.
For example, ground 499 may be coupled to the ground contact of an
input/output jack on a device. In doing so, a handshaking circuit
may receive information via a ground contact. For example, the
handshaking circuit may receive a virtual ground at ground 499 from
another handshaking circuit that has a non-zero value (e.g., 1
volt). The handshaking circuit may utilize this virtual ground to
embed information for the other handshaking circuit (e.g., impart
current pulses into the virtual ground). Moreover, a handshaking
circuit may utilize both a power and a ground contact to both send
information to, and receive information from, any number of
handshaking circuits.
[0071] Driving circuit 475 may be provided to drive the switching
characteristics of switch 471 of pulse generator 470. Driving
circuit 475 may include capacitor 476 which generates a pulse that
switches ON switch 471 by electrically coupling the gate terminal
of switch 471 to ground. Person skilled in the art will appreciate
that the capacitance of capacitor 476 may determine, at least in
part, the amount of time that switch 471 is turned ON. For example,
capacitor 476 may be configured to turn switch 471 ON for a
particular amount of time at a particular period of time. For
example, capacitor 476 may turn switch 471 ON approximately 4
microseconds every 5 milliseconds (e.g., witch may be set by
oscillator 420). Such a switching characteristic of switch 471 may,
in turn, generate a current pulse (based on the resistance of
resistor 472) that has a duty cycle of 4 microseconds divided by 5
milliseconds (or 0.1% duty cycle). In this manner, capacitor 476
may provide a LOW duty cycle current pulse in a power supply
signal. Such a LOW duty cycle current pulse may have a duty cycle
of, for example, less than 1. A LOW duty cycle current pulse may,
for example, have a duty cycle of less than 0.1%. Persons skilled
in the art will also appreciate that if resistor 472 has a
resistance of approximately 47 ohms and 2.9 volts is provided
across resistor 472, then 60 milliamps of current may flow through
resistor 472 for a voltage on node 491 of 2.9 volts. Accordingly,
pulse generator circuit 470 may produce relatively HIGH current,
LOW duty cycle current pulses. Furthering this example, as current
remains constant across a node, the handshaking circuit providing
power to node 491 will also include 60 milliamps of current.
Handshaking circuit may be configured to send different types of
current pulses (e.g., a 40 milliamp pulse and a 60 milliamp pulse)
in order to provide different types of instructions to the
handshaking circuit providing the power supply signal. Similarly,
the handshaking circuit providing the power supply signal may
operate in different ways (e.g., step-up or step-down the voltage
of a power supply signal) based on different instructions the
handshaking circuit receives back through the supplied power supply
signal.
[0072] Persons skilled in the art will appreciate that switch 481
may, for example, not be turned ON until a handshaking process is
complete. Accordingly, for example, a proper handshake may need to
occur before the primary circuitry of a device (e.g., a portable
music player) is able to utilize a power supply signal from node
491. Such a handshake may, for example, cause node 491 to
electrically couple to node 494. Current pulses may, for example,
be continually applied after a handshaking process completes, such
that when two devices are disconnected, the initiating handshaking
circuit can detect a loss of receipt of the correct current pulses
and can step-down the voltage of the supply voltage to a safe and
protected level (e.g., 2.9 volts).
[0073] Persons skilled in the art will appreciate that switch 481
may isolate node 491 from node 494 such that, for example,
microphone circuitry 480 may be coupled to node 491. Persons
skilled in the art will appreciate that the frequency of current
pulses of a responding handshaking circuit may also be changed to,
for example, provide different types of information to an
initiating handshaking circuit. Modulation techniques may also be
utilized when generating current pulses in order to enhance the
security of a connection. In this manner, the current pulses may be
encrypted via modulation techniques such that an initiating
handshaking circuit that receives the current pulses may know the
modulation scheme applied to the current pulses and may demodulate
the current pulses in order to decrypt the information stored in
the current pulses. In this manner, handshaking circuits may be
provided that communicate using encrypted information that is
transmitted over a power supply line.
[0074] FIG. 5 shows handshaking circuit 500 that may, for example,
provide a power supply signal to a device and determine whether
such a device includes a handshaking circuit operable to
communicate with handshaking circuit 500. More particularly,
handshaking circuit 500 may provide a power supply signal at a
particular voltage (e.g., LOW or HIGH) at node 592. Handshaking
circuit 500 may also receive, for example, current pulses at node
592 while handshaking circuit 500 is delivering a power supply
signal.
[0075] Current pulses created by a handshaking circuit (e.g.,
handshaking circuit 400 of FIG. 4) may be provided to node 592
while handshaking circuit 500 is providing a power supply signal at
node 592. Current pulse detector 560 may be utilized, for example,
to detect incoming current pulses. Persons skilled in the art will
appreciate that a current pulse detector may also recognize
different types of current pulses and may react differently
depending on the type of current pulses that are received.
Generally, sense resistor 561 may be utilized to sense changes in
current and may provide different voltage signals to comparator 562
to determine whether the appropriate current pulses have been
received. Handshaking circuit 500 may include any number of
comparators to sense any number of different types of current
pulses. Similarly, handshaking circuit 500 may include any number
of sense resistors to sense any number of different types of
current pulses. Current mirrors may be utilized to provide these
resistors with a current identical to the one on a particular node
(e.g., a power supply node).
[0076] When an appropriate current pulse is detected, the output of
comparator 562 may provide a logic HIGH signal. In doing so, pulse
stretching circuit 511 may trigger the generation of a pulse. Pulse
stretching circuit 511 may, for example, generate pulses that have
a duration longer than those created by the output of comparator
562. In fact, pulse stretching circuit 511 may, for example,
generate pulses that have a duration that is multiple times longer
(e.g., twice as long) as the period of pulses from node 592. Pulse
stretching circuit 511 may also be re-triggerable in that the
circuit may restart generating a pulse when enabled. In this
manner, pulse stretching circuit 511 may not have to wait until a
pulse is finished generating in order to generate a new pulse. As
such, pulse stretching circuit 511 may, for example, provide a
constant signal to node 593--without interruption--so long as
current pulses are sensed by pulse detector 560.
[0077] Delay circuit 520 may be provided to delay the signal
generated from pulse stretching circuit 511. For example, the
characteristics of resistor 521 and capacitor 522 may be chosen to
implement a particular time delay (e.g., 0.5 seconds). For example,
the voltage across capacitor 522 may build-up over time and may, at
a predetermined time, enable switching circuit 530 by causing the
output of comparator 531 to go LOW. In turn, the output of
comparator 531 may disable voltage regulation circuit 540 and
enable switch 551 such that the voltage of the power supply signal
provided to node 592 is stepped up from a safe, protected voltage
(e.g., 2.9 volts) to a primary power supply voltage (e.g., 5.0
volts). More particularly, when power regulation circuit 540 is
disabled, switch circuit 550 is turned ON and primary power on node
591 is electrically coupled with node 592.
[0078] Before current pulses are received at node 592 and detected
by pulse detection circuit 560, voltage regulation circuit 540 may
be enabled such that the primary power supply signal on node 591
may be stepped-down by voltage regulation circuit 540 to a
particular voltage (e.g., 2.9 volts). While device 541 is enabled,
switch circuit 550 is OFF such that the power supply signal on node
591 does not directly couple with node 592. Accordingly, device 541
steps-down the voltage of the power supply signal on node 591 and
provides this stepped down voltage on node 592 as a result of, for
example, the characteristics of switch 542, switch 543, resistor
544, resistor 545, and capacitor 546.
[0079] Persons skilled in the art will appreciate that a jack on a
device may either be a male connector, female connector, or may
take a shape that is neither male nor female. Similarly, a plug on
a cable may either be a male connector, female connector, or may
take a shape that is neither male nor female.
[0080] Persons skilled in the art will appreciate that current
pulses may be generated such that the average current for these
current pulses is LOW (e.g., 50 microamps) although the individual
current pulses have a relatively HIGH current (e.g., 60
milliamps).
[0081] From the foregoing description, persons skilled in the art
will recognize that this invention provides handshaking between
devices. In addition, persons skilled in the art will appreciate
that the various configurations described herein may be combined
without departing from the present invention. It will also be
recognized that the invention may take many forms other than those
disclosed in this specification. Accordingly, it is emphasized that
the invention is not limited to the disclosed methods, systems and
apparatuses, but is intended to include variations to and
modifications thereof which are within the spirit of the following
claims.
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